This application relates generally to gas turbine engines and, more particularly, to methods and apparatus for inspecting gas turbine engine compressor and turbine rotor assemblies.
At least some known gas turbine engines include a compressor for compressing air, which is mixed with a fuel and channeled to a combustor wherein the mixture is ignited within a combustion chamber for generating hot combustion gases. The hot combustion gases are channeled downstream to a turbine, which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator.
Known compressors include a rotor assembly that includes at least one row of circumferentially spaced rotor blades. Each rotor blade includes an airfoil that includes a pressure side and a suction side connected together at leading and trailing edges. Each airfoil extends radially outward from a rotor blade platform. Each rotor blade also includes an attachment portion, such as, a dovetail that extends radially inward from the platform, and is used to mount the rotor blade within the rotor assembly to a rotor disk or spool. More specifically, at least some known rotor disks include a plurality of circumferentially spaced axially oriented dovetail slots that are sized to receive a respective one of the plurality of rotor blades therein.
During operation, the rotor blades may be subjected to environmental and loading forces that may cause in-service cracking of the blades. Known inspection techniques are limited in their ability to assess the integrity of the blades while the blades are in-place. More specifically, a visual inspection only permits a limited examination of the blades for cracks in the airfoil and in a very limited area of the dovetail. To thoroughly examine the blades where cracking may originate, at least a portion of the engine casing may need to be removed to facilitate removal of each blade, and subsequent inspection of the blades with visual, magnetic particle, or liquid penetrant techniques. However, because of labor and cost constraints such techniques may be impracticable in some instances.